Living in the Las Vegas desert, one
must make wise use of the precious
resource of water. Several times, I have
come home to find a water geyser in
my backyard from the irrigation
system. Once, to my surprise, I
opened a water bill that was
outrageous. An irrigation valve had
been stuck on for about a month. This
leads to the inescapable conclusion
that irrigation systems are much like
kids: really nice to have, but you have
to keep a watchful eye on them.

By Donald Palmer

To help me keep that watchful eye, I decided to build the Irrigation Watch: a Microchip PIC based system that would monitor the water
flow that feeds my irrigation system. My modus
operandi is regulated by a Hunter X-Core irrigation
control that has four outputs for 24 VAC solenoid
controlled irrigation valves.

The system also has a normally closed “rain
sense” input to turn the system off when rain is
detected by a remote sensor. This provides the
means to turn off the irrigation system if a problem
is detected by the Irrigation Watch.